# Restore-UDCData.ps1 - Idempotent UDC data restore for the manifest engine.
#
# Triggered by the GE Shopfloor Enforce scheduled task (runs as SYSTEM, every
# user logon + every 5 min). Standard-machine manifest entry uses
# DetectionMethod=Always so this fires every cycle; the script self-decides
# whether there's actually any work to do.
#
# CONTRACT:
#   - 99% of cycles: no backup waiting -> exit 0 in ~1 second, no side effects
#   - 1 cycle (the one after Backup-UDCData lands a backup for this PC's bay):
#     stop UDC, copy CurrentData.json + ArchivedData/ to C:\ProgramData\UDC,
#     move consumed backup to <bay>\migrated\<timestamp>\, write
#     restore.manifest.json, restart UDC. After this, root is empty so the
#     check returns "no backup waiting" again on subsequent cycles.
#
# DESIGNED FOR THE SWAP WORKFLOW:
#   New PC gets pre-imaged with real machine number + locked down, sits in
#   storage. Days/weeks later, tech runs Backup-UDCData on old PC -> backup
#   lands on share. Tech swaps PCs. New PC powers on at the bay -> ShopFloor
#   autologon -> manifest engine fires this script -> backup detected ->
#   restored -> UDC opens with prior history intact.
#
# Replaces the placeholder->real trigger in Update-MachineNumber.ps1 for the
# pre-imaged-then-swapped case (where the trigger fired at imaging time, before
# the backup existed). Update-MachineNumber.ps1's branch still handles the
# secondary case (tech used 9999 placeholder + sets number at bay) - both
# triggers safely no-op if the other already consumed the backup.

[CmdletBinding()]
param(
    [string]$BackupShareRoot = '\\tsgwp00525.wjs.geaerospace.net\shared\dt\shopfloor\backup\udc',
    [string]$UdcDataDir      = 'C:\ProgramData\UDC',
    [string]$UdcExePath      = 'C:\Program Files\UDC\UDC.exe',
    [string]$UdcSettingsPath = 'C:\ProgramData\UDC\udc_settings.json',
    [string]$Site            = 'West Jefferson'
)

$ErrorActionPreference = 'Stop'
$logDir = 'C:\Logs\UDC'
if (-not (Test-Path $logDir)) {
    try { New-Item -Path $logDir -ItemType Directory -Force | Out-Null } catch { $logDir = $env:TEMP }
}
$logFile = Join-Path $logDir 'Restore-UDCData.log'

function Log {
    param([string]$Msg, [string]$Level = 'INFO')
    $ts = Get-Date -Format 'yyyy-MM-dd HH:mm:ss'
    $line = "[$ts][$Level] $Msg"
    Add-Content -LiteralPath $logFile -Value $line
    Write-Host $line
}

# --- Resolve local machine number ---
if (-not (Test-Path -LiteralPath $UdcSettingsPath)) {
    # No UDC installed yet. Manifest engine will catch up later if/when it lands.
    exit 0
}
try {
    $json = Get-Content -LiteralPath $UdcSettingsPath -Raw | ConvertFrom-Json
    $mn = $json.GeneralSettings.MachineNumber
} catch {
    Log "Failed to parse $UdcSettingsPath : $_" 'ERROR'
    exit 0
}
if (-not $mn -or $mn -eq '9999' -or $mn -notmatch '^\d+$') {
    # Placeholder or invalid - the placeholder->real trigger in
    # Update-MachineNumber.ps1 will catch it when the tech sets a real number.
    exit 0
}

# --- Probe for a waiting backup ---
$bayDir = Join-Path $BackupShareRoot $mn
$srcCur = Join-Path $bayDir 'CurrentData.json'
$srcArc = Join-Path $bayDir 'ArchivedData'

if (-not (Test-Path -LiteralPath $srcCur)) {
    # Most-common path: no backup waiting. Exit silently to keep enforce-cycle
    # logs clean. (Manifest engine still records that the entry ran.)
    exit 0
}

# We have a backup. From here on, log everything.
Log "==============================================="
Log "UDC data backup detected at $bayDir - restoring."
Log "Hostname:       $env:COMPUTERNAME"
Log "Machine number: $mn"

# --- Stop UDC.exe so CurrentData.json isn't locked ---
Get-Process UDC -ErrorAction SilentlyContinue | ForEach-Object {
    try {
        $_.Kill()
        $_.WaitForExit(5000) | Out-Null
        Log "Stopped existing UDC.exe (PID $($_.Id))"
    } catch {
        Log "Could not stop UDC.exe (PID $($_.Id)): $_" 'WARN'
    }
}
Start-Sleep -Milliseconds 500

# --- Ensure local UDC data dir exists ---
if (-not (Test-Path -LiteralPath $UdcDataDir)) {
    New-Item -ItemType Directory -Path $UdcDataDir -Force | Out-Null
}
$localCur = Join-Path $UdcDataDir 'CurrentData.json'
$localArc = Join-Path $UdcDataDir 'ArchivedData'

# --- Copy CurrentData.json ---
$copiedCur = $false
try {
    Copy-Item -LiteralPath $srcCur -Destination $localCur -Force -ErrorAction Stop
    $copiedCur = $true
    Log "Copied CurrentData.json ($((Get-Item $localCur).Length) bytes)"
} catch {
    Log "Copy CurrentData.json failed: $_" 'ERROR'
}

# --- Copy ArchivedData/ ---
$copiedArc = $false
$arcFiles  = 0
$arcBytes  = 0
if (Test-Path -LiteralPath $srcArc) {
    try {
        if (Test-Path -LiteralPath $localArc) {
            Remove-Item -LiteralPath $localArc -Recurse -Force -ErrorAction SilentlyContinue
        }
        Copy-Item -LiteralPath $srcArc -Destination $localArc -Recurse -Force -ErrorAction Stop
        $arcItems = Get-ChildItem -LiteralPath $localArc -Recurse -File -ErrorAction SilentlyContinue
        $arcFiles = $arcItems.Count
        $arcBytes = ($arcItems | Measure-Object Length -Sum).Sum
        $copiedArc = $true
        Log "Copied ArchivedData/ ($arcFiles files, $arcBytes bytes)"
    } catch {
        Log "Copy ArchivedData/ failed: $_" 'ERROR'
    }
}

# --- One-shot consumption: only move backup -> migrated/ if BOTH copies succeeded ---
# (If one failed, leave the live backup in place so the next cycle can retry.)
$consumeOk = ($copiedCur -and ($copiedArc -or -not (Test-Path -LiteralPath $srcArc)))
if ($consumeOk) {
    try {
        $stamp    = Get-Date -Format 'yyyy-MM-ddTHH-mm-ssZ'
        $migDir   = Join-Path $bayDir 'migrated'
        $migStamp = Join-Path $migDir $stamp
        if (-not (Test-Path -LiteralPath $migDir))   { New-Item -ItemType Directory -Path $migDir   -Force | Out-Null }
        if (-not (Test-Path -LiteralPath $migStamp)) { New-Item -ItemType Directory -Path $migStamp -Force | Out-Null }

        Move-Item -LiteralPath $srcCur -Destination (Join-Path $migStamp 'CurrentData.json') -Force -ErrorAction Stop
        if (Test-Path -LiteralPath $srcArc) {
            Move-Item -LiteralPath $srcArc -Destination (Join-Path $migStamp 'ArchivedData') -Force -ErrorAction Stop
        }
        $bakManifest = Join-Path $bayDir 'backup.manifest.json'
        if (Test-Path -LiteralPath $bakManifest) {
            Move-Item -LiteralPath $bakManifest -Destination (Join-Path $migStamp 'backup.manifest.json') -Force -ErrorAction SilentlyContinue
        }

        $restoreManifest = [ordered]@{
            RestoredAt          = (Get-Date -Format 'o')
            DestinationHostname = $env:COMPUTERNAME
            DestinationUser     = [System.Security.Principal.WindowsIdentity]::GetCurrent().Name
            MachineNumber       = $mn
            CurrentDataBytes    = (Get-Item $localCur).Length
            ArchivedDataFiles    = $arcFiles
            ArchivedDataBytes    = $arcBytes
            RestoredVia         = 'Restore-UDCData.ps1 (manifest engine, on logon)'
        }
        $restoreManifest | ConvertTo-Json | Set-Content -Path (Join-Path $migStamp 'restore.manifest.json') -Encoding UTF8

        Log "Backup consumed -> migrated\$stamp\"
    } catch {
        Log "Move-to-migrated failed (data IS restored locally, but live backup remains - next cycle will retry consumption): $_" 'ERROR'
    }
} else {
    Log "Restore incomplete - leaving live backup at $bayDir for retry next cycle." 'WARN'
}

# --- Relaunch UDC with the current machine number args so it picks up the
#     restored CurrentData.json. UDC's vendor autostart in HKLM\Run will also
#     fire on the next user logon, so this is belt-and-suspenders for the
#     same-session case (e.g. tech is at the keyboard during the restore). ---
if ((Test-Path -LiteralPath $UdcExePath) -and $copiedCur) {
    try {
        Start-Process -FilePath $UdcExePath -ArgumentList @("`"$Site`"", "-$mn")
        Log "Relaunched UDC.exe with `"$Site`" -$mn"
    } catch {
        Log "UDC relaunch failed: $_" 'WARN'
    }
}

Log "==============================================="
exit 0